Paganism
Before Christianity was practiced in European countries, people believed in paganism.

The word pagan refers to country dweller or rural, when Christianity established Pagans were considered as heathens.
Heathen means someone that has no religion and will never go to heaven. Or simply not a Christian.

The Catholic church wanted the pagans to convert to Christianity.

They did this by blending in pagan festivals with Christian festivals.
Pagans were an agricultural society, so many of their beliefs were to honour and worship spirits to improve their crops.
Pagan festivals were to celebrate:
1) harvest (Samhain)- Christians turned this into Halloween.
2) fertility - Christians turned this into Easter.
3) winter solstice - Christians turned this into Christmas.